Automated dispenser with a paper sensing system

ABSTRACT

A dispenser for dispensing a portion of sheet product stored in a dispenser, in which a dispensed sheet portion is to be removed by tearing the sheet portion from the remaining product supply. The dispenser includes a system which detects the presence of sheet product in a region of a dispensing outlet. Upon detection of a potential user, the sensing system causes dispensing of paper, on the condition that the sheet portion is regarded as having been torn off. The system includes elements for detecting a discontinuity in the sheet product.

FIELD OF THE INVENTION

The present invention relates to a dispenser including a feeding meansdriven by a motor for dispensing a portion of sheet product stored insaid dispenser, further including a dispensing outlet through which saidsheet product is fed upon a feed command being issued by a controlmeans, and a tear means against which one area of said portion is to bedrawn so as to allow said sheet portion to be torn and removed from aremaining portion of a sheet product supply, wherein said dispenserincludes a sheet sensing means for detecting the presence of sheet in aspecific region of said dispenser proximate said dispensing outlet, saidsheet sensing means being connected to said control means, wherein saidsheet sensing means repeatedly scans said specific region at a firstscan interval for the presence of sheet product or a discontinuity ofsaid sheet product.

The invention furthermore relates, in a preferred form, to an automatictowel dispenser (preferably with paper towels stored inside thedispenser housing on a cylindrical supply roll) of the electricallypowered type, preferably a battery powered type (but which could also beAC powered or powered by a combination of AC and DC power supplies).Such a dispenser may have an IR sensor system or another sensor systemused to control dispensing of products such as paper sheets (e.g. paperhand-towels) when the presence of a possible/potential user is detected,preferably without physical contact of the user with the dispenser (orthe sensors) being required for initiating the dispensing sequence.

BACKGROUND TO THE INVENTION

Dispensers of the aforementioned type are known from US2003/0169046 A1.

This document discloses a sheet (paper sheet) sensing means in the formof two sets of sensors (pairs of IR emitters and receivers) in thedischarge chute of the dispenser to protect it from ambient infrared(IR), which sensors can detect a leading edge of a paper sheet to bedispensed and then dispense paper as required when a user is present. Ina so-called “hanging towel” mode (“sheet hanging” mode), sheet materialmay be dispensed when absence of material is detected, as this indicatesthat a towel has been torn off. In both situations, the sensors registerthe position of a piece of sheet material after the feed mechanismstarts to operate so that a leading edge is detected during a firstpredetermined time period. After detection, a predetermined furtheramount of material can be dispensed during a second predeterminedperiod. At the end of the feeding cycle which lasts for thepredetermined second time interval, a towel length of the requiredlength will have been dispensed for grasping and tearing by a user. Whena towel of predetermined length is irregularly torn, one of the sensorsmay be uncovered while the other one is covered, in which case thecontrol system detects a torn state and allows a new towel to be issuedon the next detection of a user.

While the aforementioned dispenser thus provides means for detecting anirregularly torn sheet, it however relies on the fact that a sheet istorn off irregularly at or after the intended time for being torn off,namely after the dispensing operation by the motor has finished. It alsorelies on the fact that, at that time (after motor feeding has stopped)at least one of the sensors will then still be uncovered.

However it has been recognised that an impatient user may tear off asheet while it is being fed, so that when the remainder of thepredetermined length of sheet (which has not been torn off) continues tobe fed out of the discharge chute, the remaining part will cover bothsensors. In the aforementioned device this circumstance would of courseleave a quantity of sheet still present at the outlet and thus detectedby both sensors, causing the system to register that a towel has notbeen torn off. This can prevent dispensing of a new piece of paper toweluntil the piece blocking the sensors is removed. Furthermore, as thesensors are in the discharge chute which is designed not to allow accessby human fingers, the dispenser may remain inoperable due to thepremature tearing that occurred, since no further sensors are locatedoutside the discharge chute to determine that a paper sheet ofsufficient length is not present.

SUMMARY OF THE INVENTION

The present invention aims at overcoming the aforementioned problem,such that a prematurely torn sheet will be recognised by the controlmeans.

Further problems which are overcome, will be apparent upon reading thisspecification.

The features of the independent claim result in a dispenser whereby thesensing means for the sheet product, in particular paper, are caused toscan substantially continuously during the entire operation of the motorwhich drives the feeding means (e.g. the feed roller), such thatwhenever a discontinuity in the sheet product is detected (i.e. whenevera lack of sheet product is detected) by the sensing means during motoroperation, the sheet sensing means issues a signal to the control meansto indicate that sheet material has been torn off. Thus, irrespective ofwhether the motor continues to run until the end of the time at which apredetermined length of sheet product should be dispensed, or whetherthe motor stops as soon as (or soon after) a discontinuity is detected,the control means will register that the sheet has been torn off.

In this way, the control means is in a position to be able to issue asheet feed command (i.e. to issue a command which will activate thedrive motor circuitry so as to initiate the dispensing of a furtherportion of sheet product of a predetermined length) on the next occasionthat a user's presence is detected e.g. by a user sensing means, withouthaving to forego the advantage of preventing dispensing when a sheetportion has been fully dispensed but not torn off.

The terminology “tear means” is used herein to mean a means againstwhich an area of said sheet product can be drawn so as to cause saidsheet to rupture so that it may be removed. Typically such a tear meansmay be in the form of a metal plate with a serrated edge. However theedge need not be serrated. Likewise other tear means may be used such asfor example a series of plastic sharpened areas or the like or simply asingle continuous sharp edge. Further possibilities may also beenvisaged and will be clear to a skilled person.

A “scan” as referred to herein is the emittance of e.g. an infrared (IR)signal, and the activation of a detection means to be able to detect thesignal e.g. reflected IR. Reflected signals (e.g. reflected IR signals)need not be used however, as an emitter and receiver could be placedopposing each other, whereby the sensor acting as a receiver can bearranged to directly receive the emitted signal (e.g. IR) when no sheetproduct blocks the path between the emitter and receiver and not toreceive the signal from the emitter (or to receive only a relatively lowamount of signal from the emitter) when sheet product blocks the pathbetween emitter and receiver. If IR is used as the emitted signal, thismay be continuous or pulsed, whereby if pulsing is used the pulsingfrequency may be set to cover only a small frequency range (e.g.centered for e.g. up to 3 or 4 kHz on both sides of a central frequencyof e.g. 15 kHz) so as to make the IR signal detection moredistinguishable from received ambient IR.

During such a scan (i.e. an individual scan comprising emitting a signalof some type which is intended to be received by a receiver for theemitted signal), the (pulsed) IR will be emitted for a brief period oftime, normally only a few milliseconds, e.g. one to two milliseconds.When a “scan interval” is mentioned herein, this refers to an intervalof time between individual scans, i.e. an. interval between a firstemitted signal and a second emitted signal.

A “discontinuity” being detected in the sheet product as mentionedherein, refers to a lack of sheet product being detected during the scanperiod. The sensing means is thus arranged to detect the presence ofsheet product until such time as the product is severed and thusproduces a gap, or opening, with respect to the remaining sheet product.

A “specific region” of the dispenser is also mentioned herein. Such aspecific region means a region, which in terms of its position is afixed area with respect to a part of the dispenser, said specific regionbeing a region across which, or past which, the sheet product passeswhen it is being dispensed by the feeding means from a product supplystored in the dispenser, towards the dispensing outlet. In dispensersusing a pair of rollers causing feeding of sheet product through the niptherebetween upon driven rotation of one of the rollers, the specificregion will suitably start after the nip between these rollers.Likewise, where a tear edge or tearing means is provided in thedispenser, against which dispensed sheet product may be drawn by a userin order that a dispensed piece of sheet product is removed from therest of the product supply, the specific region is suitably locatedslightly after (downstream of) the tear edge or tear means. “Slightlyafter” hereby means that the start of the specific region very closelyfollows the tear edge location of the tear means, such as by an amountof typically less than 2 cm, normally less than 1 cm.

Where the term “upstream” or “downstream” is used herein, this refers toa position in the direction of feeding sheet product (i.e. from insidethe dispenser housing to outside the dispenser housing via thedispensing outlet).

When the sensing means is operating to perform a scan at a first scaninterval during the time in which said motor is causing the feedingmeans (typically a feed roller) to feed sheet product towards thedispensing outlet, the first scan interval is preferably set to a valuewhich is shorter than the time taken for tearing off a piece of sheetmaterial against the tear means. Values of up to 50 ms are most suitedto this task even if longer time intervals could be used. More suitablyhowever, 20 ms or less may be used for most sheet product dispenserswhich tend to be less than 40 cm in width. Values below 10 ms are evenmore preferable to account for very fast tear speeds and a 3 ms intervalis even more preferred. While a still shorter interval could be used,this would use more power which could be significant if a batteryoperated dispenser is used.

Any locations on the dispenser or sensors etc., are defined with respectto the dispenser in its normal position of use and not mounted upsidedown or the like. Thus, the lower part of the dispenser is intended tobe at the bottom. Likewise the lateral direction of the dispenser is ina generally horizontal direction.

Where a vertical direction or plane is referred to, this is normallyintended to refer to the generally vertical direction. When thedispenser is mounted on a true vertical wall, the vertical direction isthus a true vertical direction. If however, the wall is slightlyinclined by a few degrees, a vertical direction referred to with respectto the dispenser will also be an inclined vertical by the same amountand in the same direction as the wall inclination.

In terms of the user sensing means, a preferable type is a touchlesstype of sensor system (often referred to as a “hands free” or“non-contact” sensor system), such as an 10. IR sensor system, althoughother touchless types of sensing means such as capacitative types may beused.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail with reference tocertain non-limiting embodiments thereof and with the aid of theaccompanying drawings, in which:

FIG. 1 shows a schematic side view of a sheet material dispenser,depicting a schematic view of a first user sensing system detectionzone, whereby a side panel of the dispenser has been removed to showschematic details of the paper roll and paper transport mechanism,whereby also the sheet sensing means has been removed for clarity,

FIG. 2 is a sectional side view of a sheet sensing means proximate theoutlet of a dispenser similar to that in FIG. 1 whereby the user sensingsystem (shown in FIG. 1) is removed, and the sheet sensing means isincluded,

FIG. 3 is a schematic view illustrating the position of sheet materialin relation to the sheet sensing means, presenting a discontinuity inthe sheet material,

FIG. 4 shows an illustration similar to FIG. 3, wherein sheet materialhas stopped moving at the end of feeding, in a position where nodiscontinuity is detected,

FIG. 5 shows an illustration similar to FIG. 2 but without the presenceof sheet product, but with an underlying strip of material on an area ofthe dispenser covering a specific region proximate the outlet,

FIG. 6 shows a plot of emitted signal amplitude against time

FIG. 7 shows a plot of received signal level against time, for a seriesof received IR reflections occurring due to the emitted IR pulses in auser sensing system,

FIG. 8 shows a block diagram of the basic system elements of anembodiment of a dispenser,

FIG. 9 shows an RC circuit used for effecting wake-up of themicroprocessor in the MCU so as to perform a scan, and

FIG. 10 shows an alternative version of the RC circuit depicted in FIG.9.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a dispenser 1 in side view, whereby dispenser 1 attached atits rear side to a wall W (the means of attachment are not shown but maybe of any suitable type such as screws, adhesive, or other attachmentmeans), whereby the rear surface of the dispenser lies against said wallW which is normally vertical.

The dispenser 1 comprises a housing 2, within which is located a productsupply, in this case a supply of paper in a roll 3. The roll 3 issuitably a roll of continuous non-perforated paper, but may alsocomprise perforated paper. Also located in the housing 2 is a sheetfeeding means 4 (e.g. paper transport mechanism) preferably in the formof a modular drive cassette with its own casing 15, which can preferablybe removed as a single unit from the housing 2 when the housing 2 isopened.

FIG. 1 schematically shows the paper roll 3 and the sheet feeding means4 which feeds sheet material 7 from the roll towards a discharge outlet(see further description below) 8 upon rotation of the motor M. Thesheet material roll 3 and the sheet feeding means 4 is shown in a vastlysimplified form, whereby this includes a drive roller 5 engaged with acounter roller 6, whereby a portion of the sheet product (e.g. paper) 7is shown located between said rollers 5, 6, with the leading edge ofsaid sheet product 7 ready to be dispensed at a discharge outlet 8formed in the housing 2 at the lower side thereof.

The drive roller 5 is shown schematically connected to an electricaldrive motor M powered by batteries B. A gearing, typically in a gearbox,may be included between the motor drive shaft and. the drive roller 5.Suitable batteries may supply a total of 6V when new. Operation of themotor M causes drive roller 5 to rotate and to thereby pull paper sheet7 from the paper roll 3 by pinching the paper between the nip of therollers 5 and 6. Upon actuation, the motor rotates, thereby withdrawing(paper) sheet from the roll 3, which also rotates so as to allow paperto be moved towards the discharge opening 8. Other forms of sheetfeeding means for withdrawing paper from a roll and dispensing it may beused. The details of the sheet (paper sheet) feeding means as such arehowever not important for an understanding of the invention. Suchdevices are also well known per se in the art.

It will also be understood from the aforegoing that drive roller 5 andcounter roller 6 may have their functions swapped such that the counterroller 6 could be the drive roller which is operably connected to thedrive motor (and thus the drive roller 5 depicted in FIG. 2 only acts asa counter roller in contact with roller 6, normally with sheet materialsuch as paper or towel material in the nip therebetween).

Although the principle of operation is explained using paper in the formof a continuous paper sheet in a wound roll, it is to be understood thatthe dispenser may be used to dispense other sheet products from aproduct supply, such as a continuous piece of paper in concertina formatfor example. Alternative sheet products may be dispensed by the device.It is also possible that other dispensing devices are tagged on to thedispenser (such as an air freshener activated for example once everye.g. 5 or 10 minutes, or once upon a certain number of towels beingdispensed).

The motor M is at rest (not in operation) when no paper is to bedispensed. The motor M is rotated when the feeding means 4 is triggered(by a control means) to dispense paper through the discharge opening 8.The operation of the motor M is controlled by a control means in theform of a master control unit (see FIG. 8) connected to a user sensingsystem e.g. comprising sensors 9-13, of which two sensors 10 and 12 maybe emitters, preferably IR emitters, and three sensors 9, 11, and 13 maybe receivers, preferably IR receivers. Such (IR) emitters and receiversare well known in the art and typically comprise diode structures.

The emitters and receivers are shown (FIG. 1) placed on the rearmostside of the discharge outlet 8. Other arrangements of sensors are alsopossible such as all sensors placed on the front-facing side of theoutlet, preferably in a straight row along the discharge outlet. Thesensors could alternatively be placed on either side of the dischargeoutlet (e.g. emitters on one side and receivers on the other side) andlikewise extend along the discharge outlet. The discharge outlet couldhowever be placed elsewhere.

The dispenser 1, upon detection of a possible user (e.g. without anycontact of the user with the dispenser or the sensors) for a sufficienttime in a detection zone thus causes the dispenser to determine that auser is present and, when certain conditions are fulfilled, to dispensesheet material. Dispensing in this case is performed by the frontportion of the sheet product 7 being discharged automatically throughdischarge opening 8 (i.e. a laterally extending opening, generally inthe lower part of the housing, and preferably feeding out downwards).This allows the user to grasp the sheet product 7 and to draw it againsta tear means 16, such as the sharp cutting edge shown in FIG. 1,proximate the discharge opening 8, so as to tear (and/or cut) and removea portion 24 of the sheet product 7. The location of the tear means 16may be varied. It may also be on the opposite side (i.e. side closer tothe front of the dispenser) of the discharge outlet 8.

In one example of a touchless-type user sensing system, a user detectionzone 14 is shown in FIG. 1 in side view. The user detection zone willhowever generally be a volume (extending across the lateral direction ofthe device when viewed from the front) and, in the example shown, isinclined downwardly and forwardly of the discharge opening at an anglex° of preferably between 20° to 30° to the vertical axis Y. To producesuch a volume, a set of at least two emitters and three receivers may beused, arranged along the lateral extent of the discharge outlet.

However, the invention described herein is not dependent on theinclusion of any particular user detection system, even though use ofthe same type of sensing means for user sensing and for sheet materialsensing is advantageous since the overall number of circuit parts can bereduced. Advantageously, the user sensing means may include an active IRdetection system (i.e. at least one IR emitter and at least one IRreceiver) and the sheet sensing means may also include an active IRdetection system with at least one IR emitter and at least one IRreceiver. When such systems are used respectively for the sheet sensingmeans and the user sensing means, it is however advantageous if the IRemissions from the (paper) sheet sensing means do not interfere withthose from the user sensing means and vice versa. This can be achievedby the relative positioning of the emitters and receivers of therespective means, and/or by providing a different pulsed IR frequencyfor the respective means (i.e. both during emitting and receiving),where pulsed IR is used in either means.

Referring to FIG. 2, the discharge portion 2 of the dispenser 1 isprovided with a discharge outlet 8 which is arranged between one wallsurface 19 of the housing on which the tearing means 16 is located and awall portion 20 in which sensors 17, 18 of sheet sensing means arelocated. These sensors may be partially or completely recessed withrespect to the housing portion 20 (or a support unit carried by thehousing portion 20), such that IR is directed (here in the form of atrunconic shape) towards a specific region 21 (see FIG. 3) by e.g.sensor 17 which may be an (IR) emitter. Sensor 18 may be an (IR)receiver. The emitted IR signal from emitter 17, in the absence of paper(FIG. 3), is not reflected back towards receiver 18 since the specificregion 21, which is e.g. a surface of a housing panel, is arranged notto reflect IR back to receiver 18. This may be done by a specific angleof the surface 19 so as to reflect IR away from receiver 18, and/or byusing an IR non-reflecting surface, such as a dark or black surface inthe form of e.g. a rectangular or other shaped strip of black or darkmaterial 23 (for use in the case that the sheet material is a lightcoloured sheet material, e.g. white, greyish white or grey sheetmaterial). Alternatively the area may be coated or painted to provide anIR non-reflecting surface.

When sheet product (e.g. paper) is present over a major part of surface21, there is however a reflection of IR back to receiver 18. The amountof received IR is converted to a received signal value (e.g. a voltagelevel) and this value is compared to a threshold value. When thethreshold value is exceeded, this informs the control means that paperis present. The threshold value is set appropriately for this purpose,and may be adjusted individually (manually or automatically) to takeaccount of individual types and colour of the sheet product (inparticular paper). When no signal or a very low signal is received byreceiver 18, the value of the signal will not surpass the thresholdvalue and the control means is thus set to assume that no paper ispresent in the sheet sensing means detection zone (i.e. sheet product 7is not in front of the specific region 21).

The sheet sensing means including sensors 17, 18 performs a scan at ascan interval. The scan can be performed at a first scan interval and atleast a second scan interval. The first scan interval is significantlyshorter than the second scan interval. At the first scan interval, thesheet sensing means will, via suitable control circuitry and software,perform a first scan repeatedly (i.e. a scan is performed repeatedlywith a time between each individual scan equal to said first scaninterval). During the single scan, a signal is emitted which can bedetected by a receiver. In the case of an IR emitter, this emits IR andan IR receiver is activated to receive IR. The signal is emitted for avery short time (e.g. 1 to 2 ms) and this is emitted on a repeatingbasis at each scanning interval. A first scanning interval may be up to50 ms, although better results are achieved at intervals less than 20ms. More preferably the scanning interval is less than or equal to 5 msand most preferably less than or equal to 3 ms. At a short firstscanning interval of around 3 ms, the IR receiver may also be constantlyswitched on for detecting IR while the IR emitter is switched on andoff, although even the IR receiver can be switched on and off if desiredin synchronism with the IR emitter.

The first scan interval is used for detecting the presence of sheetproduct in a virtually continuous manner during driving of the feedingmeans motor M. In other words, the first scan interval should be shortto allow a virtually continuous scanning. The first scan interval shouldpreferably be chosen to be shorter than the time taken, at an estimatedmaximum tear speed by a user, to tear off a sheet product, and thus avalue of 3 ms is most preferable for this scan interval so as to allowany discontinuity in the paper (even when torn fast by a user) to bedetected.

The first scan interval is applied to the sheet sensing means by thecontrol means so as to repeatedly scan at said first scan interval. Thisfirst scan interval is used when the control means has received a sheetfeed command causing start of the motor M driving the feeding means. Thefirst scan interval is maintained between individual scans until themotor M ceases to operate (i.e. from the beginning of the motoroperation to the ceasing of motor operation to dispense an amount ofsheet material). A second scan interval, considerably longer than saidfirst scan interval, e.g. between 5 and 50 times longer, such as e.g. asecond scan interval of 0.17s between scans, will preferably be usedonce the motor has ceased to operate at the end of said dispensingoperation using said first scan interval.

During the scanning operation at the first scan interval or the secondscan interval, whenever a discontinuity of paper is detected this willresult in a signal being received by the control means which is below apredetermined threshold (as explained above).

Under normal circumstances, a user will wait until the motor M hasstopped and will then take hold of the piece of sheet material 7 andtear it against the tear means 16, such that the dispensed material 24can be removed from the remainder of the material in the dispenser 1.The removal of the dispensed sheet material will then cause the sheetsensing means to detect a discontinuity (situation shown e.g. in FIG.3).

However, in accordance with the invention even if the sheet is torn offduring dispensing (while the motor M is operating), a discontinuity inthe sheet will still be detected because the discontinuity is registeredas it passes across the sensors 17, 18, even though the sheet materialcontinues thereafter to be dispensed across the specific region (i.e. tothe situation shown in FIG. 4), due to the fact that when the leading(torn) edge of the sheet material passed the sensors, it is detected asa discontinuity, even though upon further dispensing the sheet materialagain substantially covers the specific region 21 (as also shown in FIG.4). Thus, by scanning at the (shorter) first scan interval, a signal issent to the control means indicating that a discontinuity occurred. Theshort scan interval thus allows temporary discontinuities to bedetected.

In these circumstances, a control flag can be set in the control meansmemory by software, indicating that paper has been torn off,irrespective of the whether the paper is present afterwards in front ofthe specific region at the end of dispensing action, which would, in theabsence of such means, indicate that sheet material is present and wouldneed to be torn off before continuing with a further dispensing cycle.

In this way, even though the specific region 21 may be covered and astrong IR reflection is received from the sheet product 7 (i.e. areceived IR value producing a signal value above a set threshold value),the dispenser operates as though there were no sheet product present atthe outlet 8 waiting to be torn off. Thus when a further piece of sheetproduct is to be dispensed (e.g. as controlled by the user's presencebeing detected by a user sensing system) this will not be prevented bythe sensors 17, 18 issuing a signal (due to the second scan intervalbeing used after the motor M has ceased operating to dispense sheetproduct) that sheet product (i.e. the dispensed portion) is stillpresent waiting to be torn away by a user.

In the arrangement shown in the Figures, the specific region 21resulting from IR emitted by emitter 17 and a further region 22 fromwhich IR is reflected are not entirely overlapping. These areas couldhowever be made to overlap. A discontinuity can be more easily detectedwhen there is a small area of overlap so that a small specific region isexamined, whereby any discontinuity will produce a large change in theamount of IR received.

To improve accuracy, other sheet sensors (not shown), similar to sensors17 and 18, could be located at other locations around the outlet such asadditionally, or alternatively, at the ends of the outlet 8 from wherethe paper emerges when being dispensed. Nevertheless a locationgenerally at the lateral centre of the discharge outlet 8 is found to bepreferred as a sheet discontinuity after tearing is invariably mosteasily detected at the centre of its width. This may be due to the factthat sometimes the lateral ends of a torn dispensed sheet are not tornoff in a way to be detected easily whereas the centre portion isinvariably torn.

The dispenser is preferably arranged to deliver a predetermined lengthof sheet material on each activation of dispensing (i.e. each dispensingcycle). This may be measured by various means such as timing means forstarting and stopping the motor M after a predetermined time, or bydetecting the amount of motor rotation and stopping the motor whenrequired, etc. The predetermined length can be set in the dispensercontrol means, preferably adjustably set such as by a variable resistoraccessible for example to an attendant who has access to the inside ofthe dispenser. However, in order that as little sheet product aspossible is left hanging from a dispenser when a discontinuity has beendetected (which hanging sheets may, in the case of paper toweldispensers, be a matter of hygiene concern), in one embodiment of theinvention, the detection of a discontinuity during motor operation may,apart from registering in the control means that a sheet has been tornoff (as described above), additionally cause a signal in the controlmeans to be issued to immediately cease operation of the motor M. Themotor M would otherwise continue to dispense a predetermined length ofsheet product as stated above. Due to the fact that the sheet product isregistered as having been torn off however, this will not inconveniencea user, since re-activation of dispensing to issue further sheetmaterial is possible. Also, the stopping of the motor upon adiscontinuity being detected has a type of self-teaching function forthe user who will then often realise that premature tearing of the(paper) sheet before the predetermined length has been fully dispensedwill cause him/her a small delay due to needing to reactivate thedispenser to issue more sheet product.

Also a time control may be built in to the control means to preventre-activation of the feeding means 4 until a predetermined time haselapsed e.g. a time between 2 and 5 seconds. This helps to preventunintended use of the dispenser which can otherwise result in all towelmaterial being emptied in a rather short time.

The tear means 16 are placed upstream of the specific region 21 acrosswhich the paper passes during dispensing as shown e.g. in FIG. 2. Thedistance in the feed direction of the sheet material 7 between the tearmeans 16 and the specific region 21 may suitably be of the order of oneto four cm, preferably less than three cm.

As explained above, the control means may include e.g. a memory or aregister in which the status from a previous dispensing action can berecorded. The status may be “torn off” or “not torn off” for example.The memory can be simply written in a certain location thereof on eachdispensing cycle (i.e. feeding motor start to feeding motor stop) whenregistering a discontinuity or not. This can be done by setting a flagin the memory or register as soon as a discontinuity appears. In thecase that a discontinuity is detected, whether this be during thedispensing cycle or afterwards, the control means will thus have a “tornoff” status. Further activation of the dispenser will allow a new pieceof sheet product to be dispensed through outlet 8. If no discontinuityis detected either during or after the dispensing cycle (i.e. the timeduring which the motor operates), the control means will have a “nottorn off” status and the control means then controls the motor so thatthe portion of sheet material that has been dispensed but not torn offmust be torn off before further sheet product is dispensed.

The control means maintains a condition (i.e. a control status) not toissue a sheet feed command, even when a user is present and hasactivated the dispenser (e.g. by being detected by the user sensingsystem) when the status of “not torn off” is present in the controlmeans. To check whether the sheet portion has been torn off or not afterthe dispensing cycle is complete (i.e. during a time with ceasedoperation of the motor) and to save power, one or (if required) morefurther single sheet sensing scans are performed at a second scaninterval which is considerably longer than the first scan interval untilsuch time as the portion 24 is torn off. After a long period of time(e.g. more than 300 seconds) the second scan interval may be increasedto a third longer scan interval.

The dispenser may also include a reset means, which after apredetermined time (e.g. 10 minutes) may cause the memory to reset suchthat the result of a previous scan in which paper is regarded as havingbeen dispensed but still not torn off is erased from memory. In thisway, when a user again activates the dispenser by being detected by auser sensing means, further sheet material will be dispensed as if nopaper were present at the outlet. This also provides a failsafe settingfor the case that an incorrect sensing occurred by the sheet sensingmeans.

When a user sensing means is present which performs a scanning functionto check for the presence of a user (see description further below), thetiming of the second scan interval (longer than the first scan interval)for the sheet sensing means can suitably be made to be the same as thescanning interval in the user sensing means used for the time when nouser has been detected (i.e. a scan interval t1 as explained below).Alternatively, it may be made a multiple or a fraction of this. Forexample, where a suitable value of 0.17 seconds is used as a time forscanning for the presence of a possible user in the user sensing means,the second scan interval of the paper sheet sensing means may be set to0.17 seconds or to twice this time or another multiple thereof. This canbe achieved by using both a timing circuit (e.g. an RC circuit asexplained with regard to FIG. 9 or FIG. 10) and software programming.

The method by which one or more single scans are performed in an IRsheet sensing means may be the same as that which is explained below inrelation to the description of an IR user sensing means performingscans.

When a part of a user's body enters detection zone 14 (see FIG. 1), theuser sensing system comprising i.a. sensors 9 to 13 sends a signal tothe control means MCU indicating that a user is present, which causesthe motor M to turn to dispense a portion of sheet product.

The emitters 10, 12 of the user sensor means mentioned earlier arearranged via the control means which may be part of the control meansdescribed above and which may comprise control circuitry as known per sein the art, to emit pulsed IR at a narrow frequency band of for exampleabout 15 kHz±0.5% (to reduce effects of background IR). The receivers 9,11, 13 (also mentioned earlier), are arranged to detect the emitted IRwhich is reflected against objects (stationary or moving) back towardsthe receivers. Such objects may be regarded as background or as apotential user as explained below.

FIG. 6 shows a series of individual scans (i.e. of a pulsed IRemission), of a user sensing means, at a first user scanning rate havinga time between individual scans of t1 (i.e. a scan interval of t1), asecond user scanning rate having a time between individual scans of t2(i.e. a scan interval of t2), where t2 is shorter than t1 and a thirduser scanning rate having a scan interval of t3 where t3 is greater thant1 and t2. The scan interval is measured as the time from the start ofone single emitted scan pulse to the time of emitting the nextindividual scan pulse. Each of the individual scans is here shown, in anexemplary manner, as having the same pulse intensity. A further time t4is shown which is a predetermined time or a predetermined number ofpulses separated by time t1 (i.e. at the first user scanning rate) whichneeds to elapse before the control means alters the scanning rate to thethird, slowest user scanning rate with time interval t3. The pulse widthof each pulse is preferably generally constant.

The user scanning interval t1 is set at a constant level to lie between0.15 to 1.0 seconds, preferably to lie between 0.15 to 0.4 seconds, i.e.such that each individual user scan pulse is separated by an equal timet1. The time t1 can be varied. A suitable rate to optimise the devicefor battery power saving and reaction time to dispensing has been foundto be about t1=0.17 seconds. The second user scanning rate is alwaysfaster than the first user scanning rate and t2 is set to lie preferablybetween 0.05 to 0.2 seconds, preferably between 0.08 and 0.12 secondsbetween scans. The time t2 can however be varied to be another suitablevalue, but preferably lies between 30% to 70% of t1. Time t3 may be setat for example between 0.3 and 0.6 seconds, although a longer time t3 isalso possible, such as 1 second or even longer. However, for emittancecircuit time triggering (in particular by using an RC triggering circuitusing the RC time constant to cause a discharge of current to themicroprocessor for initiating the timing operation) it is most suitableif t3 is set to double the length of t1. Thus t3 may be set at 0.34seconds in the case when t1 is 0.17 seconds. The initial time t1 can bemade variable, for example via a variable resistor operated from outsidethe device, although typically this will be factory set so as to avoidunintentional alteration of time t1 which is unsuitable in certainsituations.

Time t4 may be e.g. between 30 seconds to 10 minutes and may also bevariably set in the device. A suitable value may be about 300 seconds,although may also be more where it is desired to save further power.

Although not shown, it will be apparent that additional time periods mayalso be set in the device with intermediate time periods (i.e.intermediate between the values of t1 and t2 values, or intermediatebetween t2 and t3 etc.) or even greater time periods, dependent onoperating conditions, although the use of three different user scanningrates has been shown to take account of most situations with goodperformance in terms of reaction time and power saving.

As can be seen in FIG. 6, after four scans S1-S4 at a time interval oft1, in the embodiment shown, the first user scanning rate changes to thesecond faster user scanning rate with interval t2 and continues at thesecond scanning rate for two further scans S5 and S6.

FIG. 7 shows a sample of the possible received signal level (receivedsignal strength) of the received signals R1-R7 caused in response toemitting scan pulses S1-S7.

The approximate background IR level is Q0.

When S1 is emitted and there is no user present, the background levelreceived at R1 will be approximately at level Q0. Likewise at scan S2,the level of IR received is also close to Q0 and thus causes noalteration of the first scanning rate. At scan S3, the received signallevel R3 is above background level, but only marginally (e.g. less thana predetermined value, for example less than 10%, above background IRlevel) and thus the first scanning rate is maintained. Such smallchanges (below the predetermined level) above and below Q0 can occur dueto temporary changes in moisture levels or persons moving at a longerdistance from the dispenser, or stray IR due to changes in sunlightconditions or temperature conditions around the dispenser.

At scan S4, the received signal level has reached/surpassed thepredetermined value of e.g. 10% above background IR, so the sensor meansand its control assumes that a user is present and sheet material isrequired. In order to be able to react faster when the user is assumedto wish that a piece of sheet material (e.g. a towel) is dispensed, thescanning rate may increase to the second user scanning rate.

If level R5 received on the next scan S5 also fulfils the criteria ofbeing at, or more than, a predetermined level above background IR (e.g.at or greater than 10% above background IR in accordance with thecriteria used for the previous scans) the sensor system records via acounter (e.g. in a memory or another form of register) a singledetection above the predetermined level and then issues a further scanS6 at interval t2 to check whether the received IR is still at or abovethe level of 10% greater than background IR Q0. As shown in FIG. 5, thisis the case for scan S6, and the sensor system control (comprising bothsoftware and a microprocessor in a preferred form) then immediatelyissues an output to the motor M to start the motor turning in order todispense a product (e.g. a portion of paper sheet 7 from roll 3). Inthis case, i.e. when two consecutive scans are above the predeterminedlevel, the system has thus determined that a user is in a zone requiringsheet material to be dispensed. The motor M thus starts to drive thefeed means to dispense sheet product 7 through the discharge opening 8as explained previously, during which the sheet sensing means operatesas described previously at the first scan rate.

It is preferable to allow any two of three consecutive user scans to beabove the predetermined level, although the number of scans to dispensecould be any two out of e.g. four consecutive scans, or even furthercombinations.

In the case shown in FIG. 6, after a towel or other sheet product 7 hasbeen dispensed, the system alters the second user scanning rate back tothe first so as to save power. Scan S7 is thus emitted at time t1 afterscan S6. The second user scanning rate can however be maintained forlonger if desired.

In the case shown in FIG. 7 (corresponding to the emissions from FIG.6), where the user has torn off a piece of paper which has beendispensed from the dispenser and thus the level of IR radiation receivedat R7 is below the predetermined level (e.g. a level of 10% or moreabove Q0). The predetermined level of 10% can be varied. For example thepredetermined level above background level can be up to 90% or more,even up to 95% or more, above background IR. This allows for example afar greater distinction of the reflection from a user's hands comparedto any non-desired received IR in the pulsed bandwidth of e.g. 12 to 18kHz.

After a period of inactivity of time t4, scan rate with a scan intervalt3 may be used.

The background level of IR may vary over time. To take account of thisin the user sensing means, a moving average of the most recentlyrecorded IR received signals R can be used to alter the level Q0 on acontinuous basis. For example, four (or more or less than four) mostrecently received IR signal values can be used to form the average valueof background signal level by dividing e.g. the sum of the four mostrecent received signal levels by four for instance. As each new value ofIR is received, the oldest value of the four values is moved out of thecalculation (e.g. by removing it from a register or store of most recentvalues in the control circuitry) and calculating a new average based onthe most recent values.

By using a moving average of background IR level, the further advantageis obtained that when a user who has just withdrawn a towel or otherproduct keeps his/her hands at the dispensing outlet, the received IRlevel will remain high. However, to prevent a user in this way causingdischarge of a large amount of product, e.g. paper towel material, theuser's hands will be regarded as being background IR when they arerelatively stationary and thus dispensing will not occur. To dispensefurther sheet material (e.g. paper), the user must therefore movehis/her hands away from the dispenser sensors to allow a reading of“true” background IR (i.e. background IR without the user's hands beingpresent too close to the device). Only upon renewed movement of theuser's hands towards the user sensing means sensors can a sheet bedispensed again.

It will also be appreciated that as the batteries of the dispenserdischarge over time, the power supplied to the sensors may also beaffected which may cause less efficient operation. To prevent thisoccurring and thus to ensure a stable voltage is available for supply tothe sensors in the user sensing means and/or in the sheet sensing means,until a time close to total battery depletion, a constant current sinkmay be employed. Such constant current sinks providing voltage stabilityare well known in the art of electronics and thus are deemed to requireno further description here, although it will be understood that theiruse in the sensing circuitry for such a dispenser as described herein isparticularly advantageous. The amount of extra energy required tooperate a constant current sink is negligible and thus use of such adevice is barely noticeable on battery useable lifetime.

The power supplied to the emitters of the user sensing means may bevaried by automatic control, in particular to achieve optimised levelsto take account of background conditions, to provide reliable and fastsensing and to provide dispensing without using unnecessary power.

FIG. 8 shows a block diagram of the basic system of one embodiment of adispenser which may be used for the invention, in which the portionshown in dotted lines includes the basic components for IR signalmodulation, IR emission and IR reception used to submit a sensing signalto the A/D modulation of the master control unit (MCU) which unitcontains a microprocessor. This can be used for both the user sensingmeans and the sheet sensing means.

Box 101 and 102 denote IR emitter(s) and receiver(s) respectively,corresponding generally to the previously described emitters 10, 12 andreceivers 9, 11 and 13. The emitter 17 and the receiver 18 of the sheetsensing means can be arranged to fit in the control circuit in the sameway as emitters 10, 12 and receivers 9, 11, 13 as these are also IRemitters and receivers. The hand symbol indicates that IR radiation fromemitter(s) 101 is reflected by a user's hand back to receiver(s) 102.This is the same as for a sheet sensing means, whereby the sheetreflects IR from emitter 17 back to the receiver 18.

Unit 103 is a photo-electric converter for converting the received IRsignal before it is passed to filtering and amplification unit 104 wherethe band pass filter and amplification circuits operate to amplify thereceived signal around the central frequency in a limited band width andto thereby suppress other IR frequencies relatively. The signal is thenpassed to a signal rectification unit 105, since the IR signal is an ACsignal. From the unit 105, the signal passes into the A/D module of theMCU. The use of pulsed IR is however not an absolute requirement, inparticular for the sheet sensing means.

The output of the PWM module 106 (pulse width module) is controlled bythe MCU such that a square wave signal from the PWM can have its dutycycle varied by the MCU to adjust the DC voltage to the emitter circuitsand thus the power of the IR signal emitted. The PWM 106 is connected toa D/A converter 107 and into an IR emitter driving circuitry unit 109which includes the constant current sink mentioned previously. Into thesame IR emitter driving circuitry is also fed a signal from a phasefrequency detection module 108 which issues a 15 kHz (±0.5%) impulsemodulated signal (or another frequency of modulated signal as consideredappropriate) so as to drive the emitters 101 via the emitter drivingcircuitry 109 to emit modulated IR signals for short intervals (e.g.each signal is emitted for about 1 ms). In this regard it should benoted that before the modulated signal is emitted, the MCU should firsthave already put the filter and amplification circuit unit 104 for thereceived signal into operation for a short period, e.g. 2.5 ms, beforeemitting a modulated pulse, so as to allow the receiver circuit tostabilise, so as to reliably detect reflected IR from the emitted IRsignal. As explained previously, for the paper sensing means, thereceiver circuit may be set to be on constantly due to the very shortscan interval used during motor operation.

Since the unit 104 is already in operation when the IR scanning pulse isemitted, and since the filters and amplification unit are centeredaround the central frequency of the emitted pulse, there is no need tosynchronise the timing of the emitted pulse and the received pulse toany further extent.

The signal from unit 109 feeds into the IR emitter on/off control unit110. The input/output module 118 of the MCU also feeds into the unit 110to be turned on and off as required to thereby perform an IR scan viathe emitter 101.

In order to activate the microprocessor (i.e. wake it up to perform auser scan or a sheet sensing scan at a certain rate as mentioned above),RC wake-up circuitry 115 may feed into the MCU into a wake-up detectionunit 114. For the sheet sensing means during the time the motor is inoperation, the MCU can preferably be maintained constantly awake, as thesheet product scan interval is very short. Unit 117 is an externalinterrupt detection unit.

From the input/output module 118 is a feed to unit 119 which can beregarded as the motor driving circuitry which drives the motor M whenthe sensor system (which preferably includes the MCU and software) hasdetected that sheet product should be dispensed due to the determinationof the presence of a user in the dispensing zone 14.

Further peripheral units 111, 112 are respectively a paper sensing means(the operation of which is described in more detail above with respectto FIGS. 2 to 5), and a low power detection circuit (i.e. for detectingbattery power). The connections for this are not shown, but will besimilar to those used for the user sensing means. Unit 116 indicatesbattery power which is used to drive the MCU and also all otherperipherals and the motor M. Unit 120 may be motor overload circuitrywhich cuts off power to the motor for example when sheet product becomesjammed in the dispenser or when there is no sheet product in thedispenser. Unit 121 is a sheet product length control unit (which mayitself be variably adjustable by manual operation e.g. of a variableresistor or the like) which operates such that a predetermined, constantlength of sheet product is dispensed each time the motor is made tooperate to feed a length of sheet product 7 through the dischargeopening 8. This unit 121 may also include a low power compensationmodule by which the motor under lower power is made to turn for a longerperiod of time in order to dispense the same length of sheet product,although the unit may simply be a pulse position control system wherebythe rotation of the motor M is counted in a series of pulses and therotation is stopped only when the exact number of pulses has beenachieved. Such a pulse position control system could include for examplea fixedly located photointerruptor which can detect slots in acorresponding slotted unit fixed to the motor drive shaft (oralternatively on the drive roller 5 operably connected to the drivemotor). Unit 122 may be low sheet product detection circuitry and unit123 may be used to indicate whether the casing is open or closed. Thiscan for example be used to provide automatic feeding of a first portionof sheet product from the roll 3 through the discharge opening when thecase is closed, e.g. after refilling with a new roll of e.g. paper, sothat the person refilling the dispenser is assured that the device isdispensing properly after having been closed.

Although not shown here, a series of warning or status indication lightsmay be associated for example with various units such as units 111, 112,120 to 123 to indicate particular conditions to a potential user ordispenser attendant or repairman (e.g. if the dispenser motor is jammedor the dispenser needs refilling with paper or the like).

FIG. 9 shows one embodiment of an RC control circuitry which can be usedto give a timed wake-up of the microprocessor in the MCU. The principleof such a circuit is well known and in the present case a suitable valuefor the resistor Re is 820 kOhm and for the capacitor 0.33 microfarads.Although not shown specifically in FIG. 7, the RC wake-up circuitry usesthe input/output unit 118 of the MCU to provide the timed wake-upfunction of the microprocessor so that a scan occurs at the prescribedtime interval (t1, t2 or t3 for example). When there is a high to lowvoltage drop at the input/output, as a result of the RC circuitry, theMCU will “wake-up” and perform a scan. This wake-up leading to theperforming of a user sensing scan also requires supporting software.Likewise the length of the time t1 and/or t2 and/or t3 can suitably bemade as a multiple of the RC circuitry time constant, whereby the inputfrom the RC circuit can be used in the software to determine whether ascan is required or not at each interval. In this regard it will benoted that an RC circuit is subject to voltage changes at the input (viaVDD which is the MCU supply voltage source acquired after passingthrough a diode from the battery voltage supply). As the voltage of thebattery (or batteries) drops, there will then be an increase in the RCtime constant in the circuit of FIG. 9 and thus the times t1, t2 and t3set initially will vary as the batteries become more depleted. Forexample, with the time t1 set at the preferred level of 0.17 seconds fora battery level of 6V, a drop to depletion level of 4.2V will increasetime t1 to 0.22s. Thus, the values of t1, t2, t3 etc., as used herein,are to be understood as being the values with a fully charged batterysource. Likewise the first scan interval and the second scan intervalfor use in the sheet sensing means are also values determined at fullbattery power.

FIG. 10 shows a modified RC circuit which has the advantage of usingless current than the circuit shown in FIG. 9. In FIG. 10, three bipolartransistors are used to minimise the current used when the MCU isasleep.

By the circuitry in FIG. 9, the modification includes the use of twoinput/output ports PA7 (right hand side in the Figure) and PB7 (lefthand side in the Figure) to the MCU. The important aspect of thiscircuit is that two transistors Q2 and Q3 have been added in cascadewhich together modify the RC charge-up characteristics. The MCU PA7 pinthen gives a much sharper charge-up curve. The delay time constant forwaking up the MCU is determined by R4 and C1, which have been givenvalues of 820 kOhm and 0.68 μF respectively in the example shown. Othervalues for other time constants can of course be chosen.

The fast voltage change at port PA7 is achieved after conversion in Q2and Q3, which minimizes the time required for transition from a logicHigh voltage to a logic Low voltage level. Such a circuit as in FIG. 9can achieve about 40% power reduction during the sleep cycle compared tothe FIG. 8 circuitry for approximately the same RC time constants. Thusthe RC timing circuitry of FIG. 9 is particularly advantageous wheremaximum power is to be saved.

1. A dispenser, comprising: means for feeding driven by a motor, saidmeans for feeding being configured for dispensing a portion of sheetproduct stored in said dispenser; a dispensing outlet through which saidsheet product is fed upon a feed command being issued by a means forcontrol; means for tearing against which a region of said sheet productis to be drawn so as to allow said sheet portion to be torn and removedfrom a remaining portion of a sheet product supply; means for sheetsensing configured for detecting a presence of sheet product in front ofa specific region of said dispenser proximate said dispensing outlet,said means for sheet sensing being connected to said means for controlto form a sensing system, said means for control including a memory forstoring information from a previous scan by said means for sheet sensingperformed during operation of said motor; and means for user sensingconnected to said means for control, said means for user sensingproviding a signal to said means for control upon detection of thepresence of a user to allow said means for control to issue a sheet feedcommand, wherein said means for sheet sensing is arranged to repeatedlyscan said specific region at a first scan interval for the presence ofsheet product or a discontinuation of said sheet product during anentire operation of said motor up to ceasing of operation of said motor,and said means for sheet sensing is arranged to send a signal to saidmeans for control to indicate that sheet product has been torn wheneversaid sensing system detects a discontinuation of sheet product duringsaid entire operation of the motor, said means for control is arrangedto issue a sheet feed command when a discontinuation has been detectedin said previous scan during operation of said motor, and wherein saidmeans for control is arranged to maintain a control condition not toissue a sheet feed command if no discontinuation has been detected insaid previous scan until such time as a further single scan, during atime without operation of said motor, detects a discontinuation, and themeans for control is arranged such that, when a discontinuation has notbeen detected on a previous scan, a second single scan is performed bysaid means for paper sensing at a second scan interval after saidprevious scan during a time without operation of said motor wherein saidsecond scan interval is longer than said first scan interval performedduring operation of said motor, and wherein if sheet product is detectedduring said second single scan, a further single scan is performed on arepeating basis at said second scan interval, until sheet product is notdetected.
 2. The dispenser according to claim 1, wherein said specificregion is arranged downstream of said means for tearing.
 3. Thedispenser according to claim 2, wherein the means for control isarranged to operate the motor such that a predetermined length of sheetproduct is fed by said means for feeding at least when nodiscontinuation in said sheet product is detected during said entireoperation of said motor.
 4. The dispenser according to claim 1, whereinthe means for control is arranged to operate the motor such that apredetermined length of sheet product is fed by said means for feedingat least when no discontinuation in said sheet product is detectedduring said entire operation of said motor.
 5. The dispenser accordingto claim 1, wherein said means for sheet sensing comprises at least oneIR emitter, and at least one IR receiver arranged to receive IR emittedby said IR emitter and reflected by sheet product blocking the IR pathto said specific region.
 6. The dispenser according to claim 1, whereinsaid specific region is located on a surface of said dispenser housing.7. The dispenser according to claim 6, wherein a relatively dark area,with respect to the colour of said sheet product, is arranged on saidsurface of said dispenser housing.
 8. The dispenser according to claim7, wherein said relatively dark area is a black area covering at leastpart of said surface of said dispenser housing.
 9. The dispenseraccording to claim 8, further including a means for user sensingconnected to said means for control, said means for user sensingproviding a signal to said means for control upon detection of thepresence of a user to allow said means for control to issue a sheet feedcommand.
 10. The dispenser according to claim 1, in which said secondscan interval increases to a third longer scan interval upon apredetermined number of second scan intervals being exceeded.
 11. Thedispenser according to claim 1, wherein said first scan interval is lessthan or equal to 20 ms.
 12. The dispenser according to claim 1, whereinsaid first scan interval is less than or equal to 3ms.
 13. The dispenseraccording to claim 1, wherein the control system is arranged to supply acommand signal to the drive motor of said means for feeding to stop saiddrive motor upon detection of a discontinuation in the sheet product.14. A dispenser, comprising: means for feeding driven by a motor, saidmeans for feeding being configured for dispensing a portion of sheetproduct stored in said dispenser; a dispensing outlet through which saidsheet product is fed upon a feed command being issued by a means forcontrol; means for tearing against which a region of said sheet productis to be drawn so as to allow said sheet portion to be torn and removedfrom a remaining portion of a sheet product supply; and means for sheetsensing configured for detecting a presence of sheet product in front ofa specific region of said dispenser proximate said dispensing outlet,said specific region being located on a surface of said dispenserhousing, said means for sheet sensing being connected to said means forcontrol to form a sensing system, wherein said means for sheet sensingis arranged to repeatedly scan said specific region at a first scaninterval for the presence of sheet product or a discontinuation of saidsheet product during an entire operation of said motor up to ceasing ofoperation of said motor, and said means for sheet sensing is arranged tosend a signal to said means for control to indicate that sheet producthas been torn whenever said sensing system detects a discontinuation ofsheet product during said entire operation of the motor, a relativelydark area, with respect to the colour of said sheet product, is arrangedon said surface of said dispenser housing, said relatively dark areabeing a black area covering at least part of said surface of saiddispenser housing, and said second scan interval is the same as ascanning interval determined by a microprocessor wake-up circuit usedfor determining the scanning interval for detecting presence of a user,whereby the scan interval in the means for sheet sensing is the same as,and performed at the same time as, the scan for detection of a saiduser.
 15. A dispenser, comprising: means for feeding driven by a motor,said means for feeding being configured for dispensing a portion ofsheet product stored in said dispenser; a dispensing outlet throughwhich said sheet product is fed upon a feed command being issued by ameans for control; means for tearing against which a region of saidsheet product is to be drawn so as to allow said sheet portion to betorn and removed from a remaining portion of a sheet product supply; andmeans for sheet sensing configured for detecting a presence of sheetproduct in front of a specific region of said dispenser proximate saiddispensing outlet, said means for sheet sensing being connected to saidmeans for control to form a sensing system, wherein said means for sheetsensing is arranged to repeatedly scan said specific region at a firstscan interval for the presence of sheet product or a discontinuation ofsaid sheet product during an entire operation of said motor up toceasing of operation of said motor, and said means for sheet sensing isarranged to send a signal to said means for control to indicate thatsheet product has been torn whenever said sensing system detects adiscontinuation of sheet product during said entire operation of themotor, and said means for control is arranged to stop said means forsheet sensing from performing a scan at said first scan interval uponcessation of operation of said motor.
 16. A dispenser, comprising: meansfor feeding driven by a motor, said means for feeding being configuredfor dispensing a portion of sheet product stored in said dispenser; adispensing outlet through which said sheet product is fed upon a feedcommand being issued by a means for control; means for tearing againstwhich a region of said sheet product is to be drawn so as to allow saidsheet portion to be torn and removed from a remaining portion of a sheetproduct supply; means for sheet sensing configured for detecting apresence of sheet product in front of a specific region of saiddispenser proximate said dispensing outlet, said means for sheet sensingbeing connected to said means for control to form a sensing system; andmeans for user sensing connected to said means for control, said meansfor user sensing providing a signal to said means for control upondetection of the presence of a user to allow said means for control toissue a sheet feed command, wherein said means for sheet sensing isarranged to repeatedly scan said specific region at a first scaninterval for the presence of sheet product or a discontinuation of saidsheet product during an entire operation of said motor up to ceasing ofoperation of said motor, and said means for sheet sensing is arranged tosend a signal to said means for control to indicate that sheet producthas been torn whenever said sensing system detects a discontinuation ofsheet product during said entire operation of the motor, and said secondscan interval is the same as a scanning interval determined by amicroprocessor wake-up circuit used for determining the scanninginterval for detecting presence of a user, whereby the scan interval inthe means for sheet sensing is the same as, and performed at the sametime as, the scan for detection of a user.